Filter comprising printed circuit board and busbars

ABSTRACT

A filter for electromagnetic noise comprising: a printed circuit board ( 5 ) having conductor tracks, having a first side and having a second side opposite the first side; a first busbar ( 1 ), which is secured on the first side of the printed circuit board ( 5 ) and is electrically connected to at least one of the conductor tracks; and a second busbar ( 2 ), which is secured on the second side of the printed circuit board ( 5 ) and is electrically connected to at least one of the conductor tracks. The printed circuit board ( 5 ) is arranged between the first busbar ( 1 ) and the second busbar ( 2 ) for the insulation thereof.

TECHNICAL FIELD

The invention relates to a filter for electromagnetic noise comprising aprinted circuit board and busbars.

PRIOR ART

Electronic systems in vehicles, e.g. in motor vehicles, are becomingever more complex. The electrical parts are becoming ever more sensitiveto electromagnetic noise and are also causing ever more radiointerference. Therefore, filters for suppressing electromagnetic noise,e.g. EMI or EMC filters, are being employed more and more often inelectrical systems of vehicles. Particularly in the case of electricallydriven vehicles, this problem is particularly relevant on account of thehigh currents and the high switching speeds of current transformers.

Said filters are generally formed from a combination of one or moreconductor rails, one or more inductances and one or more capacitors. Inthis case, in existing solutions, the inductances and capacitors areconnected to the conductor rails either directly or via cables. In orderto obtain an insulation between the electrical components, eithersufficiently large distances or insulations, e.g. by potting theelectronic components, are provided. However, the existing solutionshave the problem that they do not satisfy the combination ofrequirements in vehicle construction regarding vibrations, simpleproduction in high numbers, high production quality, small spacerequirement, low weight and flexibility for different powerapplications.

SUMMARY OF THE INVENTION

It is an object of the invention to find an improved filter that bettercomplies with the combination of the requirements described.

According to the invention, this object is achieved by means of a filteras claimed in claim 1.

The arrangement of two busbars on opposite sides of a printed circuitboard in order to realize a filter has a whole series of advantages. Thebusbars remain insulated from one another by the printed circuit boardand can be arranged very close together independently of the power orcurrent intensity and/or dielectric strength for which the filter isdesigned. Additional weight owing to potting insulations is alsoobviated. In addition, complex cabling of electrical components or themounting thereof directly on the busbars is obviated, since theelectrical components now can be arranged on the printed circuit boardsimply and in a mechanically automated manner and can be connected tothe busbars via conductor tracks. Moreover, the mounting of theelectrical components, in particular of the busbars, of the capacitorsand of the magnetic elements on conductor tracks allows very robustmounting which ensures a good, reliable connection with long-termstability even under severe vibrations.

Further embodiments are specified in the dependent claims.

In one embodiment, the filter comprises at least one magnetic elementand at least one capacitor, wherein the busbars are separated from theprinted circuit board at least in the region of the magnetic element. Asa result, the magnetic elements around the busbars for realizingcurrent-compensated inductors or current transformers can be madesmaller and lighter. The capacitors as electrical components can beinstalled on the printed circuit board in a simple manner.

In one embodiment, the at least one magnetic element is ring-shaped ineach case, and each at least one ring-shaped magnetic element is pluggedby a ring opening of the magnetic element onto a projection of theprinted circuit board. This type of mounting is simple, rapid androbust.

In one embodiment, the busbars are mechanically secured on the printedcircuit board by securing means, wherein the securing meanssimultaneously ensure an electrical connection between the respectivebusbar and a corresponding conductor track of the printed circuit board.This has the advantage that complex and susceptible solderingconnections are obviated.

In one embodiment, the first busbar and the second busbar bear with acontact area directly on the printed circuit board. This allows aparticularly robust mechanical and electrical connection between busbarsand the printed circuit board.

In one embodiment, the printed circuit board has a first conductor trackarea on the first side in the region of the contact area with the firstbusbar, wherein the first conductor track area produces an electricalcontact between the first busbar and the first conductor track area.Furthermore, the printed circuit board has a second conductor track areaon the second side in the region of the contact area with the secondbusbar, wherein the second conductor track area produces an electricalcontact between the second busbar and the second conductor track area.This allows a particularly good electrical connection between thebusbars and the printed circuit board. In addition, the busbar on theprinted circuit board behaves like a conductor track.

In one embodiment, the filter comprises a metallic housing, wherein thehousing has at least one ground potential area, wherein the printedcircuit board has at least one ground conductor track area, wherein eachof the at least one ground potential area of the housing is pressed ontoa corresponding ground conductor track area by securing means and aground connection from the printed circuit board to the housing is thusproduced. This has the advantage that no additional cables between thefilter housing and the printed circuit board are necessary.

BRIEF DESCRIPTION OF THE FIGURES

The invention is explained in greater detail with reference to theaccompanying figures, in which

FIG. 1 shows a circuit of a first exemplary embodiment of a filter.

FIG. 2 shows a three-dimensional view of the first exemplary embodimentof the filter.

FIG. 3 shows a view from above of the first exemplary embodiment of thefilter.

FIG. 4 shows a sectional view through the busbars and the printedcircuit board in the region of a magnetic element of the first exemplaryembodiment.

FIG. 5 shows a view of a first side of a printed circuit board of thefirst exemplary embodiment of a filter.

FIG. 6 shows a view of a second side of a printed circuit board of thefirst exemplary embodiment of a filter.

FIG. 7 shows a first exploded view of the first exemplary embodiment ofthe filter with the printed circuit board, the busbars and the magneticelements.

FIG. 8 shows a first exploded view of the first exemplary embodiment ofthe filter with the filter and its housing.

FIG. 9 shows a circuit of a second exemplary embodiment of a filter.

FIG. 10 shows a three-dimensional view of the second exemplaryembodiment of the filter.

FIG. 11 shows a three-dimensional view of the second exemplaryembodiment of the filter before the assembly of PCB, busbars andmagnetic element.

FIG. 12 shows a first side view of the second exemplary embodiment ofthe filter.

WAYS OF EMBODYING THE INVENTION

FIGS. 1 to 8 show a first exemplary embodiment of a filter according tothe invention. The filter comprises a printed circuit board 5 havingelectrical components. Electrical components of the filter comprise afirst busbar 1, a second busbar 2, at least one capacitor and at leastone magnetic element.

The printed circuit board 5 is a board composed of an electricallyinsulating material with conductor tracks for connecting the electricalcomponents of the filter. The printed circuit board 5 has a first sideand a second side opposite the first side. In one embodiment, theprinted circuit board 5 has at least one lateral side, which is or arearranged at right angles to the normal to the printed circuit boardplane (plane of the first and second sides). In one embodiment, theprinted circuit board 5 has four lateral sides. In one embodiment, theprinted circuit board 5 has one or more cutouts and/or projections 5.1on the at least one lateral side in order to plug the at least onemagnetic element onto the printed circuit board 5 and hold said at leastone magnetic element there.

The at least one magnetic element is arranged in each case in aring-shaped fashion around the first and second busbars 1 and 2 and, inthe first embodiment, together with the first and second busbars 1, 2forms a current-compensated inductor. In this case, in a ring-shapedfashion means that the magnetic element forms a complete or at least alarge part of a closed curve around the first and second busbars 1 and2, such that the magnetic element forms a current-compensated inductorwith the two busbars 1 and 2 and the two busbars 1 and 2 are led throughthe ring opening shaped by the magnetic element. The closed curvepreferably forms a circle (torus), but in other examples may also beshaped as rectangular, square, n-gonal (polygonal) or in some other way.In the case of a torus (bagel-shaped), the cross section of thecircumferential torus bulge is preferably rectangular. This facilitatesthe securing of the ring-shaped magnetic element on a projection 5.1 ofthe printed circuit board 5. In this case, the magnetic elementpreferably forms a closed ring. However, the magnetic element can alsoform a non-closed ring or a ring composed of a plurality of partialsectors (e.g. two half-toroids).

In the first exemplary embodiment, the at least one magnetic elementcomprises two magnetic elements 4.1 and 4.2. Preferably, the latter areformed identically and/or secured on the printed circuit board 5 in anidentical way. Preferably, these two magnetic elements 4.1 and 4.2 arearranged on opposite lateral sides of the printed circuit board 5. Thetwo busbars 1 and 2 preferably extend, in principle, along alongitudinal axis through both ring openings of the two magneticelements 4.1 and 4.2.

The at least one capacitor is electrically connected to the first andsecond busbars 1 and 2 via the conductor tracks of the printed circuitboard 5. Each of the at least one capacitor is electrically connected byone of the known securing methods on the printed circuit board 5. In oneembodiment, the through-hole technology (THT) customary in powerelectronics is used, although surface-based mounting techniques such asSMD or other mounting techniques are also possible.

In the first exemplary embodiment, the at least one capacitor comprisesa current capacitor 3.1 (also called X capacitor) connected between thefirst busbar 1 and the second busbar 2, as is shown for example in thecircuit in FIG. 1. In the exemplary embodiment with two magneticelements 4.1 and 4.2, the current capacitor 3.1 is contacted with thefirst and second busbars 1 and 2 between the two magnetic elements 4.1and 4.2. Alternatively or additionally, the at least one capacitorcomprises a first ground capacitor 3.21 which is connected between thefirst busbar 1 and ground 7, and/or a second ground capacitor 3.22 whichis connected between the second busbar 2 and ground 7, as shown forexample in the circuit in FIG. 1. In the exemplary embodiment with twomagnetic elements 4.1 and 4.2, the ground capacitors 3.21 and 3.22 arepreferably contacted with the first and second busbars 1 and 2 betweenthe two magnetic elements 4.1 and 4.2. Each functional capacitor, suchas, for example, the current capacitor 3.1 and the ground capacitors3.21 and 3.22, can itself consist of a plurality of connected individualcapacitor units which are in each case individually connected to theprinted circuit board 5. In general, the capacitor units of a functionalcapacitor are interconnected in parallel with one another by means ofthe conductor tracks of the printed circuit board 5. However, a seriesconcatenation of the capacitor units is also conceivable for very highcurrents. In the exemplary embodiment in FIGS. 2 and 3, the groundcapacitors 3.21 and 3.22 and the current capacitor consist for examplein each case of two capacitor units connected in parallel.

FIG. 1 shows a first exemplary embodiment of a filter, although manyother filter circuits composed of at least one capacitor and at leastone magnetic element are possible. In one embodiment, the filter is apassive filter. In one embodiment, the filter is an EMI or EMC filter.In one embodiment, the filter is designed for a power range of greaterthan 500 W and/or a current range of greater than 50 A.

The first busbar 1 and the second busbar 2 are composed of anelectrically conductive, preferably metallic, material. The busbars 1and 2 are rigid (in contrast to flexible cables and wires). In thiscase, the first busbar 1 is secured on the first side of the printedcircuit board 5 and the second busbar 2 is secured on the second side ofthe printed circuit board 5, such that the first and second busbars 1and 2 are electrically insulated from one another by the insulatingprinted circuit board 5 and there is no risk of a short circuit. Thebusbars 1 and 2 are designed for conducting the system current. This ispreferably a DC current. Preferably, the cross-sectional area of eachcurrent conductor 1 and 2 is at least ten square millimeters, preferablyat least 20 square millimeters.

The first busbar 1 and the second busbar 2 in each case have a first endand a second end, wherein each end has a connection terminal 1.1, 2.1.In one embodiment, the cross section of the busbars at right angles tothe current direction is rectangular. This is one possibility forachieving a flat bearing area for the respective busbar 1 and 2 on theflat printed circuit board 5. In one embodiment, the ends of the busbars1 and 2 with the connection terminals 1.1 and 2.1, project beyond thelateral sides of the printed circuit board 5, such that the filter canbe connected in a simple manner to cables or plugs or other connectionsof an electrical network of a vehicle. In one embodiment, the filterfurthermore comprises a housing (not illustrated in the figures), whichencloses (preferably all) electronic components of the filter, whereinthe four ends of the two busbars 1 and 2 with the four connectionterminals 1.1 and 2.1 project from the housing.

In one embodiment, the busbars 1 and 2 are secured on the printedcircuit board 5 in each case by securing means 6, such as screws,threaded pins, clips, rivets, printed circuit board inserts (PCBinserts), soldering areas or other securing means.

In one embodiment, the secured first busbar 1 bears directly on thefirst side of the printed circuit board 5. This has the advantage thatthe first busbar 1 bears with a large area on the printed circuit board5 and thus allows a stable connection even under severe vibrations. Inone embodiment, the first busbar 1 is not arranged in a recessed manneron the first side of the printed circuit board 5. In one embodiment, thecross section of the first busbar 1 at right angles to the current flowdirection or to the longitudinal axis of the first busbar 1 is such thatit forms a planar contact area with the first side of the printedcircuit board 5. In one embodiment, the cross section of the firstbusbar 1 at right angles to the current flow direction or to thelongitudinal axis of the first busbar 1 is at right angles, with one ofthe four sides forming the contact area. Upon securing on the printedcircuit board 5, said contact area of the first busbar 1 is in physicalcontact with the printed circuit board 5, i.e. touches the printedcircuit board 5. In one embodimet, said contact area between the firstbusbar 1 and the printed circuit board 5, in the current flow direction,extends over at least 30%, preferably at least 40%, preferably at least50%, preferably at least 60%, preferably at least 70%, preferably atleast 80%, of the length of the printed circuit board 5 and/or of thelength of the first busbar 1 projected onto the printed circuit board 5.The secured second busbar 2 also bears directly on the second side ofthe printed circuit board 5, and the previous descriptions concerningthe bearing of the first busbar 1 on the first side of the printedcircuit board 5 are likewise applied to the bearing of the second busbar2 on the second side of the printed circuit board 5.

In one embodiment, the first side of the printed circuit board 5 has afirst conductor track area 10.1 in the region of the contact area withthe first busbar 1. As a result, it is possible to produce a large-areaelectrical contact between the first busbar 1 and the printed circuitboard 5. Preferably, said first conductor track area 10.1 is formedparallel to the printed circuit board plane. Preferably, the firstconductor track area 10.1 covers at least 10%, preferably at least 20%,at least 30%, preferably at least 40%, preferably at least 50%,preferably at least 60%, preferably at least 70%, preferably at least80%, preferably at least 90%, of the contact area of the first busbar 1with the printed circuit board 5. As a result, the first busbar 1 on theprinted circuit board 5 behaves like a conductor track. FIGS. 6 and 7show the first side of the printed circuit board 5 and the conductortrack area 10.1 below the first busbar 1. The electrical contact and/orthe mechanical securing can be produced by a soldering connection.Alternatively or additionally, the electrical contact can also beproduced by a pressure from the first busbar 1 on the first side of theprinted circuit board 5, said pressure being caused by the securingmeans 6. Preferably, the securing means 6 are arranged in the printedcircuit board 5 in the region of the contact area with the first busbar1 or in the region of the first conductor track area 10.1, such that thesecuring means 6 press the first busbar 1 onto the first conductor trackarea 10.1. The first conductor track area 10.1 can also be composed of aplurality of first conductor track areas separated from one another,e.g. if the first busbar 1 has different connecting points (or contactareas), e.g. upstream and downstream of the magnetic element. For thesame reason, the second side of the printed circuit board 5 has a secondconductor track area 10.2 in the region of the contact area with thesecond busbar 2 (see FIG. 5). The second conductor track area 10.2, withrespect to the second busbar 2 and the second side of the printedcircuit board 5, has features corresponding to those of the firstconductor track area 10.1 with respect to the first busbar 1 and thefirst side of the printed circuit board 5.

Alternatively or additionally, the securing means 6 electrically contactthe busbars 1 and 2 with corresponding conductor tracks of the printedcircuit board 5. This can be achieved, for example, by embodying thecutouts or threads of the printed circuit board 5 for the securing means6 with an electrically conductive, e.g. metallic, surface that isconnected to the corresponding conductor track. A sufficiently large andstable contact area between the conductor track and the correspondingbusbar 1, 2 is produced as a result. However, other contact means suchas e.g. contact areas parallel to the printed circuit board plane and/orelse soldering contacts are also possible.

In one exemplary embodiment, the busbars 1 and 2 are formed in ameandering fashion in each case in opposite directions, such that thebusbars 1 and 2 are at different distances from one another in differentregions. In one embodiment, the distance between the first busbar 1 andthe second busbar 2 is smaller in the region of the at least onemagnetic element compared with the region of the securing means 6,particularly if the securing means 6 extend through the printed circuitboard 5 onto the other side and there is the risk of a flashover orshort circuit between the securing means 6, electrically connected toone busbar 1 or 2, and the other busbar 2 or 1. In one embodiment, thedistance between the first busbar 1 and the second busbar 2 is smallerin the region of the at least one magnetic element compared with theregion of the ends of the busbars 1 and 2 that project beyond theprinted circuit board 5. This is advantageous in particular since, inthis region, the busbars 1 and 2 are no longer insulated from oneanother by the printed circuit board 5 and a larger safety distance isthus required. In one embodiment, the busbars 1 and 2 are identical; ifthey are shaped in a meandering fashion in opposite directions, they cansimply be arranged on the printed circuit board 5 in a manner rotated by180° in order to achieve the characteristic in opposite directions.

FIG. 4 shows a section through a part of the printed circuit board 5, ofthe first busbar 1 and of the second busbar 2 in the region of themagnetic element (in the ring opening thereof). Preferably, the firstand second busbars 1 and 2 are arranged on the printed circuit board 5such that the projections of the busbars 1 and 2 onto the printedcircuit board 5 at least partly overlap. As a result, the ring openingcan be made smaller and the magnetic element can be made smaller andthus lighter.

FIG. 8 shows a housing 9 of the filter. Preferably, the printed circuitboard 5 has at least one ground conductor track area 7. In FIG. 8, fourground conductor track areas 7 are arranged in the four corners of theprinted circuit board 5. Said ground conductor track areas 7 can bearranged on the first side and/or on the second side of the printedcircuit board 5. The at least one ground conductor track area 7 definesthe ground potential of the filter on the printed circuit board 5. Theground conductor track area 7 is connected to the metallic housing 9.This is for example achieved via at least one ground potential area 8 inthe housing 9, which, with the housing 9 assembled, presses against theat least one ground conductor track area 7 and thus produces the groundconnection to the housing 9. As a result, a ground connection to thehousing via an additional cable becomes superfluous. Preferably, asecuring cutout passes through the at least one ground conductor trackarea 7 and/or the at least one ground potential area 8. As a result, agood ground connection can already be obtained as a result of thesecuring of the printed circuit board 5 on the housing 9. Preferably,the housing 9 has a first shell for covering the first side of theprinted circuit board 5 and a second shell for covering the second sideof the printed circuit board 5. The two shells each have a securingcutout in the region of the at least one ground conductor track area 7and/or the at least one ground potential area 8. As a result, theprinted circuit board 5 can be compressed by means of a screw connectionbetween the first shell and the second shell in the region of the atleast one ground conductor track area 7.

FIGS. 9 to 12 show a second exemplary embodiment of a filter accordingto the invention. The filter comprises a printed circuit board 15 withelectrical components. Electrical components of the filter comprise afirst busbar 11, a second busbar 12, at least one capacitor 13 and atleast one magnetic element 14. Unless explicitly described otherwise,the description of the printed circuit board 5 and of the electricalcomponents of the first exemplary embodiment also applies to the printedcircuit board 15 and the electrical components of the second exemplaryembodiment.

FIG. 9 shows a circuit diagram for the second exemplary embodiment. Herethe filter is embodied as an active filter. The active filter comprisesa current transformer 23, an amplifying circuit 24 and a capacitor 13.The active filter is preferably an EMI or EMC filter. The filter ispreferably designed for a power range of greater than 500 W and/or anominal current of greater than 50 A.

The current transformer 23 converts the AC noise currents of the firstand second busbars 11 and 12 into a measurement current in the auxiliarywinding 27. For this purpose, the magnetic element 14 couples the firstand second busbars 11 and 12 to the auxiliary winding 27. Preferably,for this purpose, the magnetic element is arranged in a ring-shapedfashion around the first and second busbars 1 and 2 as described in thefirst exemplary embodiment. Preferably, the current transformer 23 formsa current-compensated common-mode current transformer. The auxiliarywinding 27 can be configured as a conductor track on the printed circuitboard 15. However, it is also possible to realize the auxiliary windingas wire connected to the printed circuit board 15 or one of theelectrical components of the printed circuit board 15.

The amplifying circuit 24 generates the compensation current or thecompensation voltage on the basis of the AC currents measured in thecurrent transformer.

The capacitor 13 is designed to input the compensation current or thecompensation voltage into the first busbar 11 and the second busbar 12,in order thus to extinguish the AC noise currents or voltages of thefirst busbar 11 and of the second busbar 12 at least in the range of thebandwidth of the active filter. As also described in the first exemplaryembodiment, the two capacitors 13 are in each case mounted on theprinted circuit board 15 and connected to the first busbar 11 or thesecond busbar 12 by means of conductor tracks.

As in the first embodiment, in this case the first busbar 11 is securedon the first side of the printed circuit board 15 and the second busbar12 is secured on the second side of the printed circuit board 15, suchthat the first and second busbars 11 and 12 are electrically insulatedfrom one another by the insulating printed circuit board 15 and there isno risk of a short circuit.

The first busbar 11 and the second busbar 12 in each case have a firstend and a second end, wherein each end has a connection terminal. In oneembodiment, the cross section of the busbars at right angles to thecurrent direction is rectangular. This is one possibility for achievinga flat bearing area for the respective busbar 11 and 12 on the flatprinted circuit board 15. In one embodiment, the ends of the busbars 11and 12 with the connection terminals project beyond the lateral sides ofthe printed circuit board 15, such that the filter can be connected in asimple manner to cables or plugs or other connections of an electricalnetwork of a vehicle. In one embodiment, the filter furthermorecomprises a housing (not illustrated in the figures), which encloses(preferably all) electronic components of the filter, wherein the fourends of the two busbars 11 and 12 with the four connection terminalsproject from the housing.

In one exemplary embodiment, the busbars 11 and 12 are secured on theprinted circuit board 15 in each case by securing means such as screws,threaded pins, clips, rivets, printed circuit board inserts, solderingconnections or other securing means. The embodiments for securing andfor contacting the busbars 11 and 12 with the printed circuit board 15are as in the first exemplary embodiment.

In one exemplary embodiment, the busbars 11 and 12 are formed such thatthe busbars 11 and 12 are at different distances from one another indifferent regions. Preferably, the distance between the first busbar 11and the second busbar 12 is smaller in the region of the magneticelement compared with the region of the ends of the busbars 11 and 12that project beyond the printed circuit board 15. This is advantageousin particular since the busbars 11 and 12 are no longer insulated fromone another by the printed circuit board 15 in this region and a largersafety distance is thus required. Preferably, the distance between thebusbars 11 and 12 in the region of the magnetic element, in particularin the opening of the toroidal core 14, is minimal. Preferably, thebusbars 11 and 12 are identical, and can be arranged on the printedcircuit board 15 in a manner rotated by 180°, in order to obtain thedifferent distances. In contrast to the first exemplary embodiment, thedifferent distance is realized by a greater distance from the printedcircuit board plane of the printed circuit board 15, whereas in thefirst exemplary embodiment the larger distance is achieved by a lateralarrangement in the printed circuit board plane.

The first busbar 1 and the second busbar 2 are completely overlapping inthe region of the magnetic element (in the ring opening thereof),whereas there is only a partial overlap in the first exemplaryembodiment. However, it is also possible to realize a complete overlapin the first exemplary embodiment and/or only a partial overlap in thesecond exemplary embodiment.

With the filter according to the invention it is possible to obtain asmall and light filter of high quality whose design and dimensions canbe used for a large range of voltages, currents and/or powers.

1. A filter for electromagnetic noise comprising: a printed circuitboard having conductor tracks, having a first side and having a secondside opposite the first side, a first busbar, which is secured on thefirst side of the printed circuit board and is electrically connected toat least one of the conductor tracks; a second busbar, which is securedon the second side of the printed circuit board and is electricallyconnected to at least one of the conductor tracks; wherein the printedcircuit board is arranged between the first busbar and the second busbarfor the insulation thereof.
 2. The filter as claimed in claim 1, whereinthe first and second busbars are mechanically secured on the printedcircuit board in each case by securing means leading through the printedcircuit board, wherein the securing means form a conductive connectionbetween the corresponding conductor track of the printed circuit boardand the busbar.
 3. The filter as claimed in claim 1 further comprising:at least one magnetic element arranged in a ring-shaped fashion aroundthe first and second busbars, wherein at least in the region of the atleast one magnetic element the printed circuit board is arranged betweenthe first busbar and the second busbar for the insulation thereof. 4.The filter as claimed in claim 3, wherein the distance between the firstbusbar and the second busbar is greater in the region of the securingmeans than in the region of the at least one magnetic element.
 5. Thefilter as claimed in claim 3, wherein the at least one magnetic elementis formed in each case as a magnetic toroidal core that is plugged ontoa projection of the printed circuit board, wherein the first and secondbusbars on the opposite first and second sides of the printed circuitboard are led through the ring opening of the magnetic toroidal core. 6.The filter as claimed in claim 3, wherein the at least one magneticelement together with the first and second busbars forms acurrent-compensated inductor.
 7. The filter as claimed in claim 3,wherein the at least one magnetic element comprises two magneticelements, wherein the at least one capacitor between the two magneticelements is connected to the first and/or second busbar.
 8. The filteras claimed in claim 3, wherein the at least one magnetic elementtogether with the first and second busbars forms a current transformerin order to convert noise currents in the first and second busbars intoa measurement current in an auxiliary winding.
 9. The filter as claimedin claim 3, comprising at least one capacitor, which is or are connectedto the first and/or second busbar via the conductor tracks.
 10. Thefilter as claimed in claim 9, wherein the at least one capacitorcomprises a current capacitor connected between the first and secondbusbars.
 11. The filter as claimed in claim 9, wherein the at least onecapacitor comprises a first ground capacitor, which is connected betweenthe first busbar and ground, and optionally a second ground capacitor,which is connected between the second busbar and ground.
 12. The filteras claimed in claim 9, wherein the at least one capacitor comprises afirst coupling capacitor, in order to input a compensation currentgenerated on the basis of a measurement current into the first busbar,and a second coupling capacitor, in order to input the compensationcurrent into the second busbar.
 13. The filter as claimed in claim 3,wherein the first and second busbars have in each case a first endhaving a first connection terminal and a second end having a secondconnection terminal, wherein the first end and the second end of thefirst and second busbars in each case project beyond the printed circuitboard.
 14. The filter as claimed in claim 13, wherein the distancebetween the first busbar and the second busbar is greater in the regionof the first and/or second ends than in the region of the at least onemagnetic element.
 15. The filter as claimed in claim 13, wherein thefirst busbar and the second busbar are insulated from one another by theprinted circuit board continuously except in the region of theprojecting first and second ends.
 16. The filter as claimed in claim 1,wherein the first busbar and the second busbar bear with a contact areadirectly on the printed circuit board.
 17. The filter as claimed inclaim 16, wherein the printed circuit board has a first conductor trackarea on the first side in the region of the contact area with the firstbusbar, wherein the first conductor track area produces an electricalcontact between the first busbar and the first conductor track area, andthe printed circuit board has a second conductor track area on thesecond side in the region of the contact area with the second busbar,wherein the second conductor track area produces an electrical contactbetween the second busbar and the second conductor track area.
 18. Thefilter as claimed in claim 1, wherein the filter comprises a metallichousing, wherein the housing has at least one ground potential area,wherein the printed circuit board has at least one ground conductortrack area, wherein each of the at least one ground potential area ofthe housing is pressed onto a corresponding ground conductor track areaby securing means and a ground connection from the printed circuit boardto the housing is thus produced.
 19. The filter as claimed in claim 1,wherein the filter is designed for a power range of greater than 500watts and/or for a current range of greater than 50 A.
 20. The filter asclaimed in claim 1, wherein the filter is an active filter.
 21. Avehicle comprising an electrical DC voltage network and a filter asclaimed in claim 1 connected to the electrical DC voltage network. 22.The vehicle as claimed in claim 21, wherein the vehicle is driven forlocomotion by an electric motor.